Abstract: The invention relates to apparatus for use in aligning sections of pipe with respect to each other, and more particularly to aligning two sections of pipe 30 and 32 at a predetermined angle with respect to each other so that a joint between the pipe sections may be formed by welding and the like. The apparatus includes gauge devices 16 and 18 which slidably fit upon a leg 14 of a tool 10 having a second angularly oriented leg 12 such as a carpenter's square. Each gauge device includes a vertically movable gauge element 26 having gauge indicia 34 carried thereon. The gauge element 26 is advantageously in the form of a spring-loaded plunger which may be maintained within a bore 40 of the gauge device. Means for locking the gauge device in a spaced-apart relation is provided by wing nuts 22 and 24.